As is known in the art, the use of water separators in diesel engine fuel filters is a well-known expedient to rid the oil of materials that might cause a degradation of engine performance. Many of these consist merely of a water drainage reservoir at the bottom of the fuel filter connected by a drain tube simply to the ground or possibly to a container. Some are automatically operable; others, not. For example, some contain sensors activated when the water reaches a predetermined level in the reservoir to energize a signal light located on the dashboard of the vehicle to warn the driver of the need to drain the filter. Others include electrical means to operate a solenoid valve to automatically open the drain to a discharge pipe. In most cases, the drain is simply a drain to ground.
The inventors herein have recognized a disadvantage with the prior art approaches. Namely, inventors recognized that the material collected in the separator contains a water/fuel mixture, wherein the fuel portion of the mixture may be used to reduce fuel consumption and improve emission control of the engine. In particular, the mixture may be burned in an exhaust aftertreatment device thus increasing its temperature and the temperature of any downstream exhaust aftertreatment devices. Additionally, the fuel in the water/fuel mixture may be used as reductant to reduce NOx in a NOx-reducing aftertreatment device, such as an active lean NOx catalyst (ALNC).